JPH105931A - Casting core and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To cast and form a slender hole by adding resin as bond to inorganic fiber which is a main component, and making it the core for casting. SOLUTION: The main component of the core must be inorganic fiber 10 to 200μm in diameter and 1 to 20mm in length. By adding 0.2 to 2 pts.wt. resin as bond to the inorganic fiber, and it is formed to make it the core. Mica is applied on the surface of the core. The shape of the core can be maintained by a bonding strength requiring when the inorganic fibers entwine one another, and the consumption of the bond is decreased. Gas generated by a thermal decomposition at the time of the casting is decreased. The generated gas is passed through a space among the fibers, and is easily discharged outside a casting mold. When the inorganic fiber is shorter than 10μm in diameter and is shorter than 1mm in length, its strength is lowered, a void among the fibers becomes small, and they make the gas generated at the time of the casting hard to discharge outside. When the inorganic fiber exceeds 200μm in diameter and 20mm in length, the void among the fibers becomes much, the core shrinks at the time of the casting, and a prescribed shape can not be maintained. When the quantity of the resin is little, the strength of the core is lowered, and when the quantity of the resin is much, much gas is generated at the time of the casting.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a casting core,
In particular, the present invention relates to a casting core for forming a thin hole by casting and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, a hole is formed by a casting core.
Since it is extremely inexpensive and has a high degree of freedom in shape as compared with machining, it is applied to many parts. For this reason, for forming a hole that does not require a particularly high dimensional accuracy, a hole is formed at the time of casting using a casting core.

[0003] The required performance of a casting core is that it withstands heat during casting, and that there is little gas generation that causes defects.
It is an essential condition that it can be easily taken out after casting. From these performance requirements, a sand core (collapseable core) in which a refractory material such as sand is hardened with a binder such as a resin is generally used in many cases.

[0004]

However, when a narrow hole having a diameter of less than 5 mm or a narrow gap having a width of less than 5 mm is cast-molded by casting, the conventionally used collapsible sand is not used. Since the core has no elasticity and is brittle, there is a problem that the core is broken and a hole or a gap cannot be formed into a predetermined shape. Further, even if a particularly narrow slot or gap can be formed successfully, there is a problem that it is difficult to remove sand from the product after casting.

Therefore, as a technique for providing a narrow gap in a casting, for example, Japanese Patent Application Laid-Open No. 52-93820 discloses a casting method using a paper core as a casting core material.
In the method disclosed herein, the exhaust port liner made of a heat-resistant metal is wrapped around the outer periphery by a separately prepared paper core, and is cast into the exhaust port of the engine during casting. In the manufacturing method, a narrow gap of 1 to 2 mm is formed around the exhaust port liner. According to this manufacturing method, the used paper core becomes a relatively small amount of powder due to carbonization after casting, so that it is easy to take out, and there is no problem even if it remains in the casting.

[0006] However, this manufacturing method does not form a small hole, and it is difficult to apply this method to forming a small hole as it is.

[0007] The present invention has been proposed in view of the above-mentioned problems of the prior art, and is a core used for manufacturing a precision casting having a hollow shape and an undercut shape. It is an object of the present invention to provide a casting core which can be formed into a desired shape, and has a core that is not broken during casting and can be easily removed from a product after casting, even if the core is thin.

[0008]

The casting core of the present invention comprises:
It is characterized by containing inorganic fiber as a main component and adding a resin as a binder to the inorganic fiber.

The casting core of the present invention is used for producing a casting having a hollow shape and an undercut shape, and the core has a diameter of 10 to 200 μm and a length of 1 to 20 mm. The main component is inorganic fiber of 0.2
It is characterized in that it is a molded article in which a resin is added as a binder in a range of up to 2.0 parts by weight.

Further, the present invention is characterized in that mica is applied to the outer surface of the casting core.

The present invention also relates to a method of manufacturing a core used when manufacturing a casting in which a casting core has a hollow shape and an undercut shape, wherein the core material is injected and heated into a mold. It is characterized by being manufactured by.

The present invention also relates to a method for manufacturing a core used when manufacturing a casting in which a casting core has a hollow shape and an undercut shape, wherein the core material is blown into a mold and heated. It is characterized by being manufactured by.

[0013] The core for casting according to the present invention, which contains inorganic fibers as a main component, can maintain its shape due to the binding force of the fibers entangled with each other, and can reduce the amount of binder used. Therefore, generation of gas due to casting heat can be suppressed. Also, due to the thermal decomposition of the binder, the generated gas can be easily released to the outside of the mold through the gap between the fibers forming the middle child,
The occurrence of casting defects can be prevented. For this reason, it becomes possible to form a small hole at the time of casting.

The inorganic fiber used as a component of the casting core of the present invention can be used as long as it has heat resistance and does not generate gas during casting. Inorganic fiber diameter of 10
２０20 μm and length of 1-20 mm are 10 μm in diameter
For fibers shorter than m and 1 mm in length, the amount of resin for obtaining core strength increases and the amount of gas generated at the time of casting increases, and the voids between the fibers become smaller and the gas generated at the time of casting moves out of the cavity. It is difficult to release and casting defects are likely to occur. Further, fibers having a diameter of 20 μm and a length of 20 mm or more are not preferable because the voids between the fibers are large and the core shrinks during casting, so that a predetermined shape cannot be maintained.

The resin serving as a binder can be used as long as it is thermosetting. The reason for setting the amount of the resin to 0.2 to 2.0% by weight is that if the amount is less than 0.2% by weight, the strength of the core becomes low, the predetermined shape cannot be maintained during casting, and Gas is generated by the heat during casting, which tends to cause casting defects.

Further, by using a mica coating agent, a film is formed on the outer surface of the fiber and resin molded body, so that voids inside the core remain, and gas generated during casting is easily discharged to the outside of the cavity. It is possible to prevent the molten metal from being inserted into the core.

[0017]

Embodiments of the present invention will be described below in detail with reference to comparative examples.

(First Embodiment) In a first embodiment, 1.54 g of a phenol resin is added to 100 g of alumina fiber having an average diameter of 100 μm and a length of 10 mm, and the amount of resin is 1.5% by weight. Kneaded for 30 seconds.
Next, this mixture was blown into a mold heated to 280 ° C. by a blowing machine, and after one minute, the mold was opened.
The molded body 1 shown in FIG. After masking both ends of the baseboard to be set in the mold of the molded body 1 with a tape, dipping was performed for 5 seconds into a liquid mica coating agent diluted to a specific gravity of 1.5 with water, and a 0.2 mm thick film was prepared. Coating agent 2 was coated. Thereafter, a drying treatment was performed at 80 ° C. for 30 minutes, the masking tape was removed, and a core of Embodiment 1 having a diameter of 4 mm as shown in FIG. 1 was produced.

As shown in FIG. 2, the completed core
3 is placed at a predetermined position in the cavity 4, and casting is performed by pouring a molten metal of aluminum into the cavity 4 as shown in FIG.
The product 5 having the m cast-out hole 6 was obtained.

The core after the casting was easily removed by air blow.

(Second Embodiment) A core of the second embodiment was manufactured in the same manner as in the first embodiment, except that the diameter of the alumina fiber was 10 μm and the length was 8 mm. . In the second embodiment, a product having a cast-out hole having a diameter of 4 mm was obtained, and the core after the casting was easily removed by air blow.

(Third Embodiment) A core of the third embodiment was manufactured in the same manner as in the first embodiment except that the diameter of the alumina fiber was set to 200 μm. In the third embodiment, a product having a cast-out hole with a diameter of 4 mm was obtained, and the core after the casting was easily removed by air blow.

(Fourth Embodiment) A core of the fourth embodiment was manufactured in the same manner as in the first embodiment except that the length of the alumina fiber was changed to 1 mm. In the fourth embodiment, a product having a cast-out hole with a diameter of 4 mm was obtained, and the core after the casting was easily removed by air blow.

(Fifth Embodiment) A core of the fifth embodiment was manufactured in the same manner as in the first embodiment except that the length of the alumina fiber was changed to 20 mm. In the fifth embodiment, a product having a cast-out hole having a diameter of 4 mm was obtained, and the core after the casting was easily removed by air blow.

(Sixth Embodiment) A core of the sixth embodiment was manufactured in the same manner as in the first embodiment except that the amount of the phenol resin was changed to 0.2 g. In the sixth embodiment, a product having a cast-out hole having a diameter of 4 mm was obtained, and the core after the casting was easily removed by air blow.

(Seventh Embodiment) A core of the seventh embodiment was manufactured in the same manner as in the first embodiment except that the amount of the phenol resin was changed to 2.1 g. In the seventh embodiment, a product having a cast-out hole with a diameter of 4 mm was obtained, and the core after the casting was easily removed by air blow.

Comparative Example 1 In the first embodiment,
A core of Comparative Example 1 was produced in the same manner except that the diameter of the alumina fiber was 8 μm and the length was 6 mm. In Comparative Example 1, a gas generated during casting was not discharged out of the mold, and a casting defect occurred in the product.

(Comparative Example 2) In the first embodiment,
A core of Comparative Example 2 was produced in the same manner except that the diameter of the alumina fiber was 300 μm and the length was 15 mm. In Comparative Example 2, the core contracted during casting, and a predetermined cast hole could not be formed. In addition, a small amount of molten aluminum was inserted into the core, and a small amount of casting defects occurred due to gas generated during casting.

Comparative Example 3 In the first embodiment,
A core of Comparative Example 3 was produced in the same manner except that the diameter of the alumina fiber was 100 μm and the length was 0.8 mm. In Comparative Example 3, the fibers were so fine that core molding could not be carried out well, and a cast hole after casting could not be formed. In addition, casting defects occurred due to gas generated during casting.

Comparative Example 4 In the first embodiment,
Except that the length of the alumina fiber was 25 mm,
A core of Comparative Example 4 was produced. In Comparative Example 4, a cast hole after casting could not be formed. In addition, a small amount of casting defects occurred due to gas generated during casting.

Comparative Example 5 In the first embodiment,
Alumina fiber amount is 500 g, phenol resin amount is 0.5
A core of Comparative Example 5 was made in the same manner except that g was used.
In Comparative Example 5, core molding was not successfully performed, and a cast hole after casting could not be formed. Also, a small amount of insertion into the core of the molten aluminum occurred.

(Comparative Example 6) In the first embodiment,
A core of Comparative Example 6 was produced in the same manner except that the amount of the phenol resin was changed to 3.1 g. In Comparative Example 6, a gas generated during casting was not discharged out of the mold, and a casting defect occurred in the product.

(Comparative Example 7) In the first embodiment,
A core of Comparative Example 7 was produced in the same manner except that graphite was used as the mold wash. In Comparative Example 7, insertion of the molten aluminum into the core occurred.

Comparative Example 8 In the first embodiment,
A core of Comparative Example 8 was produced in the same manner except that no coating agent was used. In Comparative Example 8, insertion of the molten aluminum into the core occurred. Also, a small amount of deformation and a small amount of casting defects occurred in the shape of the cast hole.

(Evaluation Results) With respect to each of the above-described embodiments and comparative examples, the following evaluation was performed for each of the shape of the cast hole, the insertion of the molten metal, and the casting defect, and the results are shown in Table 1.

[0036]

[Table 1]

[0037]

As described above, the casting core and the method for manufacturing the same according to the present invention have a diameter of 10% in a casting core used for manufacturing a casting having a hollow shape and an undercut shape. ~ 200 μm, length 1-2
With a configuration in which inorganic fibers of 0 mm are used as a main component and a resin is added thereto in a range of 0.2 to 2.0% by weight as a binder, an elastic core is obtained and a thin core is obtained. An excellent effect of preventing the core from breaking at the time of casting can also be obtained. Further, since the generation of gas due to heat during casting can be reduced in the amount of the binder used, the generated gas can be easily discharged from the space between the fibers forming the core to the outside of the cavity. As a result, there is obtained an excellent effect that a fine hole having a diameter of less than 5 mm can be formed by the core at the time of casting.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a cross-sectional view of a core that has been subjected to coating after molding.

FIG. 2 is a diagram illustrating a state in which a core is set in a mold.

FIG. 3 is a diagram illustrating a cross-sectional shape of a casting obtained in the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Inorganic fiber molded object 2 Coating agent 3 Mold 4 Product part cavity 5 Casting 6 Casting hole

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical display location B22C 1/22 B22C 1/22 B 3/00 3/00 B

Claims (5)

[Claims] 1. A casting core comprising an inorganic fiber as a main component and a resin as a binder added thereto. 2. A core for use in producing a casting having a hollow shape and an undercut shape, wherein the core has a diameter of 10 to 200 μm and a length of 1 to 2.
0-mm inorganic fiber as a main component, 0.2-2.0
The casting core according to claim 1, wherein the molded body has a resin added as a binder in a range of parts by weight. 3. The casting core according to claim 1, wherein mica is applied to the casting core. 4. A method of manufacturing a core used for manufacturing a casting in which a casting core has a hollow shape and an undercut shape, wherein the core is manufactured by injection heating a core material into a mold. A method for producing a core for casting. 5. A method of manufacturing a core used for manufacturing a casting in which a casting core has a hollow shape and an undercut shape, wherein the core is manufactured by blowing a core material into a mold and heating. A method for producing a core for casting.